1. Field of the Invention
The present invention relates to a programmable multiplexing/demultiplexing system. A worldwide Integrated Service Digital Network (ISDN) is being developed, and a standardization thereof is being studied by CCITT. As well known, in the ISDN, voice, data, and image etc., signals output from many different types of terminal equipment are converted to digital signals, and various services are provided by processing these digital signals.
When constructing an ISDN, i.e., forming a new communication network, a wide range of communication apparatuses, and at the same time, communication software, must be developed, and thus from the hardware viewpoint, many kinds of large scale integrated circuits (LSI's) also must be developed. Development of the ISDN is still in the initial stages, and therefore, no specific definitions of the kinds of functions and services to be provided by the ISDN have been formulated. Under these circumstances, it is obvious that facilities which can adaptively cope with future service needs must be developed.
2. Description of the Related Art
In regard to the above, from the economical viewpoint, it is very risky to develop many new LSI's, especially since it would be difficult to cope with modifications of or additions to the functions of the ISDN by attempting to develop an exclusive LSI for each modification and addition, moreover, if an LSI has not been developed for a particular function, the costs of developing such an LSI, and the time and labor spent thereon would be unwarranted. Further, the design of a new LSI is time-consuming, and accordingly, a rapid development thereof is not possible, which means that a quick response to future service needs would be difficult to accomplish.